Influence of levels and forms of selenium associated with levels of vitamins C and E on the performance, yield and composition of tilapia fillet

Objetivou-se avaliar a influência da vitamina C (VC), vitamina E (VE) e de duas formas de selênio sobre o desempenho, rendimento e qualidade do filé de tilápia Nilótica. O experimento foi realizado num delineamento inteiramente casualizado composto por seis tratamentos, os quais foram constituídos pela adição de 100, 200 e 400 mg kg-1 das vitaminas C e E, associados com 0,1, 0,2 e 0,4 mg kg-1 de duas formas de selênio. Cada tratamento foi constituído por cinco repetições de 30 peixes cada. A dieta com 200 mg kg-1 de VC e VE + 0,2 mg kg-1 de selênio orgânico proporcionou ganho de peso, comprimento corporal e fator de conversão alimentar semelhantes aos tratamentos com 400 mg kg-1 de VC e VE + 0,4 mg kg-1 de selênio orgânico ou inorgânico. A adição de selênio orgânico à dieta melhorou o ganho de peso e o fator de conversão alimentar em comparação com o selênio inorgânico. A dieta com 0,2 mg kg-1 de selênio orgânico apresentou nível de glutationa peroxidase igual ao da dieta com 0,4 mg kg-1 de selênio inorgânico. Os rendimentos de carcaça e filé não foram influenciados pelos tratamentos, entretanto houve efeito dos tratamentos na composição química do filé.

Anaerobic bio-digestion of concentrate obtained in the process of ultra filtration of effluents from tilapia processing unit

The objective of the present study was to evaluate the efficiency of the process of biodigestion of the protein concentrate resulting from the ultrafiltration of the effluent from a slaughterhouse freezer of Nile tilapia. Bench digesters were used with excrements and water (control) in comparison with a mixture of cattle manure and effluent from the stages of filleting and bleeding of tilapias. The effluent obtained in the continuous process (bleeding + filleting) was the one with highest accumulated population from the 37th day, as well as greatest daily production. Gases composition did not differ between the protein concentrates, but the gas obtained with the use of the effluent from the filleting stage presented highest methane gas average (78.05%) in comparison with those obtained in the bleeding stage (69.95%) and in the continuous process (70.02%) or by the control method (68.59%).

Bile And Liver Metallothionein Behavior In Copper-exposed Fish.

The present study analyzed metallothionein (MT) excretion from liver to bile in Nile Tilapia (Oreochromis niloticus) exposed to sub-lethal copper concentrations (2mgL(-1)) in a laboratory setting. MTs in liver and bile were quantified by spectrophotometry after thermal incubation and MT metal-binding profiles were characterized by size exclusion high performance liquid chromatography coupled to ICP-MS (SEC-HPLC-ICP-MS). Results show that liver MT is present in approximately 250-fold higher concentrations than bile MT in non-exposed fish. Differences between the MT profiles from the control and exposed group were observed for both matrices, indicating differential metal-binding behavior when comparing liver and bile MT. This is novel data regarding intra-organ MT comparisons, since differences between organs are usually present only with regard to quantification, not metal-binding behavior. Bile MT showed statistically significant differences between the control and exposed group, while the same did not occur with liver MT. This indicates that MTs synthesized in the liver accumulate more slowly than MTs excreted from liver to bile, since the same fish presented significantly higher MT levels in liver when compared to bile. We postulate that bile, although excreted in the intestine and partially reabsorbed by the same returning to the liver, may also release MT-bound metals more rapidly and efficiently, which may indicate an efficient detoxification route. Thus, we propose that the analysis of bile MTs to observe recent metal exposure may be more adequate than the analysis of liver MTs, since organism responses to metals are more quickly observed in bile, although further studies are necessary.

Produção de micropartículas de alginato contendo Flavobacterium columnare inativada pelo método de emulsão para vacinação de peixes por via oral

Alginate microparticles were prepared by an emulsion method aiming oral controlled release of antigens to fish. The effects of emulsification temperature and impeller type on particle morphology, average diameter, and size distribution were evaluated. Microparticles contaning formalin-killed Flavobacterium columnare cells (a model antigen) were prepared and characterized regarding bacterial release and particle stability when exposed to Nile tilapia (Oreochromis niloticus) typical gastrointestinal conditions. This methodology allowed the production of microparticles containing up to 14.3 g/L of bacterin, stable at a pH range from 2.0 to 9.0 for 12 h and smaller than 35 μm.

O extrato de maracujá sobre a morfometria de hepatócitos da tilápia do Nilo

Avaliaram-se os efeitos do extrato de maracujá veiculado na dieta (0, 50, 100 e 200mg kg-1) sobre o consumo de alimento, o ganho em peso e os níveis de glicose e cortisol plasmático de juvenis de tilápias do Nilo (87,0±6,6g). Ao final do experimento (28 dias), os peixes foram eutanasiados para remoção do fígado, visando à avaliação da área citoplasmática, contagem de células e verificação dos estoques de glicogênio hepático. Os dados foram submetidos à ANOVA unidirecional, comparando-se as médias pelo Teste de Tukey (P<0,05), com posterior estudo de regressão, buscando estabelecer as curvas das áreas citoplasmáticas, em função das diferentes doses do extrato. A inclusão do extrato na dieta não afetou o consumo de alimento e o crescimento e todos os peixes apresentaram aumento da glicose e redução do cortisol plasmático, porém sem diferenças entre os tratamentos. As curvas de regressão indicaram aumento quadrático da área citoplasmática com a elevação da doses do extrato, principalmente para 100mg kg-1, resultando em uma curva dose-resposta em forma de "U" invertido. O aumento da área do citoplasma decorreu de um acúmulo de glicogênio hepático, conforme comprovado pela prova da amilase salivar. Concluiu-se que o extrato de maracujá pode ser fornecido na dieta de juvenis de tilápia, sem prejudicar o consumo alimentar e o crescimento dos animais e que o produto altera a morfometria dos hepatócitos, sugerindo a atividade de flavonóides sobre o metabolismo de carboidratos.

Efeito da lavagem e da adição de aditivos sobre a estabilidade de carne mecanicamente separada de tilápia do Nilo (Oreochromis niloticus) durante estocagem a -18 ºC

Este estudo teve como objetivo avaliar a influência da lavagem e da adição de eritorbato de sódio e tripolifosfato de sódio na estabilidade de Carne Mecanicamente Separada (CMS) de tilápia de Nilo (Oreochromis niloticus) durante 6 meses de armazenamento a -18 ºC. A CMS obtida por meio de máquina separadora de carne e ossos foi dividida em quatro tratamentos (CMS lavada com e sem aditivos, e CMS não lavada com e sem aditivos) e mantida sob congelamento a -18 ºC, por 180 dias. A estabilidade foi avaliada por meio de análises microbiológicas e determinações de nitrogênio não proteico (NNP), bases nitrogenadas voláteis (BNV), substâncias reativas ao ácido tiobarbitúrico (TBARS), pH e drip (perda de água no descongelamento). O processo de lavagem causou redução de aproximadamente 41, 44 e 66% nos teores de proteína bruta, lipídios e cinzas, respectivamente, reduzindo também os valores iniciais de NNP, BNV e TBARS. Durante o armazenamento, foram observados aumentos (p < 0,05) nos teores de NNP, BNV e pH em praticamente todos os tratamentos, exceto na CMS lavada com aditivos, que não apresentou aumentos significativos nos teores de NNP e pH. O uso de aditivos nas CMS diminuiu o drip ao longo do armazenamento, mas não alterou (p > 0,05) os teores de TBARS. Os parâmetros microbiológicos avaliados não ultrapassaram os limites permitidos pela legislação. As CMS permaneceram estáveis e em boas condições de utilização, independentemente da inclusão de aditivo, sendo viável sua estocagem a -18 ºC por 180 dias.

Utilização de levedura íntegra e seus derivados em dietas para juvenis de tilápia do Nilo

Neste trabalho, avaliou-se a adição de células íntegras de levedura e seus derivados em dietas para juvenis de tilápia do Nilo. Foram utilizados 144 juvenis machos de tilápia (peso médio de 52,1g) distribuídos em 12 tanques de fibra de vidro (250L), em delineamento inteiramente casualizado, composto por quatro tratamentos e três repetições. Os peixes foram alimentados ad libitum, duas vezes ao dia durante 60 dias, com dietas isoproteicas (28% PB) e isocalóricas (2.900kcal de ED kg-1) contendo levedura íntegra de cana-de-açúcar (LI), levedura autolisada (LA) e parede celular (PC) adicionados na proporção de 25% da proteína bruta total, comparadas com uma dieta controle (CO), sem adição de levedura. Não foram observadas diferenças significativas para conversão alimentar aparente e taxa de eficiência protéica. No entanto, o ganho em peso foi melhor nos peixes alimentados com as dietas LA (114,70g) e PC (131,03g), assim como em relação à taxa de crescimento específico (LA=1,79 e PC=1,93%), à proteína bruta no ganho de peso (LA=14,45 e PC=15,62%) e ao conteúdo corporal proteico (LA=14,89 e PC=15,67g 100g-1). As frações, a parede celular e a levedura autolisada de cana-de-açúcar podem ser utilizadas em dietas para juvenis de tilápia.

Conservação de filés de tilápia-do-nilo (Oreochromis niloticus) em salga seca e salga úmida

Acompanhou-se o desenvolvimento dos processos da salga em salmoura saturada (salga úmida) e salga seca de filés de tilápia-do-nilo (Oreochromis niloticus) e avaliaram-se algumas características indicativas de qualidade do produto durante a estocagem. Os processos foram acompanhados por 156 horas na salga úmida e por 96 horas na salga seca, e os filés salgados foram estocados, respectivamente, por 60 e 45 dias à temperatura ambiente. Os teores máximos de cloreto nos filés (14%) foram atingidos com 72 horas na salga úmida e com 36 horas na salga seca. Os filés de tilápia salgados em salmoura mantiveram as características próprias do produto por um período de 45 dias, e os submetidos à salga seca apresentaram baixo teor de umidade (6%) e alta concentração de extrato etéreo (4,6%). Recomenda-se somente o processo de salga em salmoura saturada como forma de conservação dos filés de tilápia-do-nilo.

O uso de praguicidas nas psiculturas e pesqueiros situados na bacia do rio Mogi-Guaçu

The use of pesticides has been the main strategy to prevent ectoparasites that threaten aquaculture productivity. The non regulated use of such chemicals may lead to damage in aquatic ecosystems that receive the ponds effluents, compromising environmental and consumers' health. With the aim of evaluate the use of pesticides in aquacultural practices developed in Mogi-Guacu catchment, fish farm and fee fishing owners were interviewed. Eighty-nine enterprises were visited, and was verified that about 40% uses pesticide during management practices in recent years. The diflubenzuron, methyl parathion, trichlorfon and triflumuron were the pesticides most used. In addition to the interviews, samples were taken in 3 enterprises localized in Socorro, SP (Peixe River sub-catchment) which had a pesticide usage history. It was not detected residues of the pesticides diflubenzuron, methyl parathion and dichlorvos in any water, sediments nor fishes samples from tow distinct seasons (lower and high fishing seasons). On fact, non-detected pesticides residues corroborate with the fish farmers statement to deny recently pesticide usage during management practices. Nevertheless, the lack of chemotherapeutics usage criteria and the potential hazardous due to these practices were discussed.

Caracterização físico-química e de frescor de filés de tilápia do Nilo (Oreochromis niloticus) oriundas da pesca extrativista no médio Rio Tietê/SP, Brasil

For increasing, the fish consumption in Brazil, is necessary offer products, with quality control to guarantee food safety to the consumers. The Medium Tiete river region is the largest producer of Nile tilapia (Oreochromus niloticus) from catching in the Sao Paulo state and, thus, the aim of this research was to evaluate the physical-chemical parameters (protein, moisture, lipid, ash and freshness (non-protein nitrogen, total volatile base nitrogen -TVB-N and pH) in fish fillets - Anhembi, Botucatu and Igaracu do Tiete. The data was examined further using random blocks design and submitted to test of variance analysis and Tukey Test for comparison of means. The data showed significant difference (5%) amont the places, for the centesimal composition and freshness, being found the following medium values: misture (77.9 to 81.69 g/100g), protein (13.72 to 18.25 g/100g), lipids (0.6 to 1.9 g/100g), ash (0.6 to 1.0g), NNP(61.6 to 78.0 mg/100g), pH (6.2 to 6.4) and TVB-N (5.0 to 10.5 mg/100g). The values found in the physical-chemical and freshness analysis are in according with brazilian's legislation, the processing of fish in the places studied are-irregular and cannot guarantee food safety to the consumers and the quality of the product.

FATTY ACID COMPOSITION OF ACID, BIOLOGICAL AND ENZYMATIC FISH SILAGE

The use of the fish silage as an ingredient in feed for aquatic organisms is an alternative to solve sanitary and environmental problems caused by the lack of an adequate destination for the residues generated by the fishing industry. It would also lower the costs with feed, and consequently the fish production costs, since the expenses with the feed account for approximately 60% of the total cost. The objective of this study was to evaluate the fatty acid composition of the acid silage (AS), biological silage (BS) and enzymatic silage (ES) produced from discardings of the culture and from processing residues of the Nile tilapia (Oreochromis niloticus). The values found for lipids (dry matter basis) were: 12.45; 12.25 and 12.17 g 100 g(-1) for BS, AS, and ES, respectively. The fatty acids present in the lipid fraction of the silages are predominantly unsaturated. Oleic acid was present in larger amounts (30.49, 28.60 and 30.60 g 100 g(-1) of lipids for BS, AS and ES, respectively). Among saturated fatty acids, palmitic and stearic acids were present in larger amounts. Only traces of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids were found. The silages produced from discardings of the culture and processing residues of the Nile tilapia are not a good source of EPA and DHA for fish feeds.

Oxidative stress biomarkers of exposure in the blood of cichlid species from a metal-contaminated river

The oxidative stress biomarkers of exposure, such as reduced glutathione (GSH), activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and the levels of lipid peroxidation (LPO), were measured in the blood of three cichlid fish (Oreochromis niloticus, Tilapia rendalli, and Geophagus brasiliensis) taken during two seasons from two sites, unpolluted and polluted by industrial effluents, to evaluate the effectiveness of these biomarkers in assessing the impact of water contamination. The LPO levels in the blood were higher in fish from the metal-contaminated site and the chronic exposure led to significant changes in GPx, CAT, and SOD activities in all three cichlid species. The considerable variation of responses in these cichlids to water contamination evidenced differences in sensitivity to the metal contamination and/or in the potential to respond to it highlighting the importance of using a set of related biomarkers to assess the impact of water contamination. (C) 2007 Elsevier Inc. All rights reserved.

Estimating Amino Acid Requirement of Brazilian Freshwater Fish from Muscle Amino Acid Profile

Information on nutritional requirement of some Brazilian farmed fish species, especially essential amino acids (EAA) requirements, is scarce. The estimation of amino acids requirements based on amino acid composition of fish is a fast and reliable alternative. Matrinxa, Brycon amazonicus, and curimbata, Prochilodus lineatus, are two important Brazilian fish with potential for aquaculture. The objective of the present study was to estimate amino acid requirements of these species and analyze similarities among amino acid composition of different fish species by cluster analysis. To estimate amino acid requirement, the following formula was used: amino acid requirement = [(amount of an individual amino acid in fish muscle tissue) x (average totalEAA requirement among channel catfish, Ictalurus punctatus, Nile tilapia, Oreochromis niloticus, and common carp, Cyprinus carpio)]/(average fish muscle totalEAA). Most values found lie within the range of requirements determined for other omnivorous fish species, in exception of leucine requirement estimated for both species, and arginine requirement estimated for matrinxa alone. Rather than writing off the need for regular dose-response assays under the ideal protein concept to determine EAA requirements of curimbata and matrinxa, results set solid base for the study of tropical species dietary amino acids requirements.

Feeding Dietary Mannan Oligosaccharides to Juvenile Nile Tilapis, Oreochromis niloticus, Has No Effect on Hematological Parameters and Showed Decreased Feed Consumption

Impaired immune system by environmental stressors can lead fishes to be more susceptible to diseases that limit the economic development of aquaculture systems. This study was set out to determine the effect of six levels of mannan oligosaccharides (MOS; ActiveMOS((R)); Biorigin, Lencois Paulista, Sao Paulo, Brazil) on the performance index and hematology of Nile tilapia, Oreochromis niloticus juveniles. Fish (13.62 g) were randomly distributed into 18 plastic aquaria (300 L; 20 fishes per aquarium) and fed during 45 d with a commercial diet supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1% dietary MOS, in a totally randomized design trial (n = 3); biometrical and hematological data were collected and analyzed. There were no significant differences in hematological parameters between fish fed control and MOS supplementation diets, and daily feed consumption (FC) decreased (P < 0.05) with increasing levels of dietary MOS. Dietary MOS did not increase leukocyte count and presented negative effects on FC of Nile tilapia. At 0.4% MOS supplementation, the individual weight gain was higher in absolute values but not different (P > 0.05) compared to control diet.

Digestibility of plant protein-based diets by largemouth bass Micropterus salmoides

Commercial farming of carnivorous fish demands the reduction of environmental impact of feeds; that requires minimal use of dietary animal protein. This study investigated the digestibility of diets formulated exclusively out of plant protein, added feed attractants, by the carnivore largemouth bass, Micropterus salmoides. Juvenile largemouth bass (14.0 +/- 1.0 cm) conditioned to accept artificial, dry feed were confined in polypropylene cages and fed ad libitum in three daily meals, seven experimental diets containing varying levels of vegetable and animal protein sources, added of different feed stimulants. After last daily meal, cages were transferred to cylindrical-conical-bottomed, 200-L aquaria, where faeces were collected by sedimentation into refrigerated containers, preserved and later analysed for chemical composition. Soybean meal can be used as partial substitute of animal protein in diets for largemouth bass; the poultry by-product meal shows as a good option as animal protein source in these rations. Control treatment - 50PP : 50AP - yielded best performances; the need for the use of fish meal in the formulation for carnivorous diets is, at least, questionable. Results of the digestibility trials demonstrated the importance of determining the diet digestibility, if precision in the formulation of least-cost feeds for carnivorous fish is the ultimate goal.